"I don't have any hobbies," says 24-year-old Choi Yeun Sung, who arguably works longer hours at his chosen career than does South Korea's president. "I just practice as much as I can, so I will improve." Of course many parents the world over would consider Choi's career itself a hobby, but in South Korea, being a professional video-gamer is a serious business.

Choi belongs to SK Telecom T1, a video-game team whose 20 members practice and live together in two shared luxurious apartments in a skyscraper in Seoul's financial district. For some 350 days a year, the young men wake at 10 a.m, jog for an hour, and then hit their computers or PCs, taking an hour off for lunch and another for dinner, and finally calling it a day at 3 a.m. (The gamers claim they play at their best just after midnight.) They don't spend much time outside their building, and when they do leave, it's normally only to run over to a nearby "e-stadium," an electronic gaming hall, to participate in a tournament.

Choi is probably Korea's best-known gamer, having clinched the gold medal at last year's World Cyber Games in Italy. The tall, slender champion of the computer began training when he was 16, and hopes eventually to retire a wealthy man. "I want to be rich," he says simply, and that may not be idle talk: Gamers at Choi's level of skill can earn several hundred thousand dollars a year off their keyboard and mouse  and the adulation of the nation's twenty- and thirty somethings, especially young women. Here, gaming isn't regarded as a geeky pastime, and the sport has a substantial following, even fan clubs, which ensure celebrity status for its champions as any other top athlete.

By definition, a video game immerses the player in a make-believe worlds, but the work of a professional gamer is hardly child's play. The international competitor must have the focus of a Buddhist monk and the hand-eye coordination of a neurosurgeon in order to defeat rival combatants in contests that typically last about 20 minutes. During that time, a gamer's heart rate can race to 160 beats per minute (equivalent to that of pro basketball player), while both hands work the mouse and keyboard at speeds of about 500 clicks per minute. They may be sitting down in a chair, but the sweat that pours off them suggests they're anything but couch potatoes.

"You need absolute mind control," says Ju Hoon, head coach of SK Telecom. And like most other professional sports, pro gaming takes a physical and mental toll on players  crippling backaches, shoulder pain, headaches, tired eyes and sore wrists are par for the course, explains Hoon, a graduate in sports psychology. Gaming is also highly addictive. In 2005, a 28-year-old South Korean man collapsed and died after playing StarCraft, an online game, at an Internet Café for 50 consecutive hours, during which time he had hardly slept or eaten  authorities deemed his death the result of heart failure caused by exhaustion.

Despite some criticism here over such obsessions, South Korea has three professional gaming leagues and two gaming stadiums, which are packed to the rafters when top competitors square off. Two Korean cable networks televise competitions round the clock, and practically every computer-literate Korean is aware of StarCraft, the game of choice among South Korean gamers.

To earn a spot on one of the country's 12 professional gaming teams, players must spend years honing their skills, usually by putting in the hours in the country's Internet cafés, locally known as "PC bangs."

"I have been waiting for this opportunity for a long time," says 18-year-old SK Telecom rookie Yoo Kwang Jun, who started gaming when he was 11. He works an even longer day than most other players, quitting just before dawn. You'd think the grueling practice schedules would take the joy out of the life of a gamer, but in the end, they're being paid to do something many of them would happily spend most of their waking hours doing for free.